PALM BEACH GARDENS, Fla. (AP) — Rory McIlroy abruptly walked off the course Friday at the Honda Classic, telling reporters who followed him to his car he's "not in a good place mentally." An hour later, he attributed his withdrawal to a sore wisdom tooth.

It raised serious questions about golf's No. 1 player with the Masters just more than a month away.

McIlroy already was 7-over par through eight holes of the second round when he hit his second shot into the water on the par-5 18th at PGA National. He shook hands with Ernie Els and Mark Wilson and was headed to the parking lot before they even finished the hole.

"There's not really much I can say, guys," McIlroy told three reporters before he drove away. "I'm not in a good place mentally, you know?"

He said there was nothing wrong physically. When asked about his swing, the 23-year-old from Northern Ireland replied, "Yeah, I really don't know what's going on."

About an hour after he left, McIlroy released a statement that pinned his withdrawal on dental problems.

"I have been suffering with a sore wisdom tooth, which is due to come out in the near future," McIlroy said. "It began bothering me again last night, so I relieved it with Advil. It was very painful again this morning, and I was simply unable to concentrate. It was really bothering me and had begun to affect my playing partners."

He was seen eating a sandwich on the 18th fairway.

McIlroy apologized to the tournament, saying he had every intention of defending his title at the Honda Classic. He mentioned the wisdom tooth on Twitter and said he was "gutted."

McIlroy, coming off a year in which he won a second major in record fashion, already set himself up for scrutiny when he left Titleist to sign an equipment deal with Nike that was said to be worth upward of $20 million a year.

Nike introduced him with blaring music and a laser show in Abu Dhabi, but it's been all downhill from there.

McIlroy missed the cut in the Abu Dhabi Golf Championship with rounds of 75-75. He took a four-week break, and then was eliminated in the opening round of the Match Play Championship to Shane Lowry in one of the most poorly played matches of the round.

McIlroy played 36 holes with Tiger Woods at The Medalist on Sunday and said Tuesday it was no time to panic.

"Even though my results haven't revealed it, I really felt like I was rounding a corner," McIlroy said. "This is one of my favorite tournaments of the year and I regret having to make the decision to withdraw, but it was one I had to make."

It looked more like McIlroy was sinking than rounding the corner, not difficult to do on a course with so many water hazards. And he found plenty of them.

McIlroy, who opened with a 70, hit two poor chips that led to double bogey on No. 11, and a wild tee shot to the right led to a bogey on the 13th. His round really unraveled on the par-4 16th, when he hit his tee shot to the right and into the water, took a penalty drop, and then came up short of the green and into the water again. He made a 6-foot putt for a triple bogey.

He three-putted from 40 feet, running his first putt about 10 feet by the hole, for a bogey to go 7 over. And then came the approach that found water for the third time of his short day on the 18th.

McIlroy is scheduled to play next week in the Cadillac Championship at Doral, which has no cut, and then the Houston Open. But on the first day of March, he has completed only four rounds of competition.

It was the second straight year one of golf's biggest stars failed to finish a tournament on the Florida swing. Woods withdrew after 11 holes on the final round at Doral last year because of tightness in his Achilles tendon, raising questions about the seriousness of his recurring leg injuries. He won Bay Hill two weeks later.

McIlroy at least drove off from PGA National without a helicopter camera following him.